1 . Technical Field
The present invention relates to an apparatus for transmitting and receiving wireless energy using meta-material structures having a zero refractive index.
2 . Description of the Related Art
The development of wireless communication technology is leading to a ubiquitous information environment in which anyone can exchange desired information anytime and anywhere.
Also, since most communication and information devices are dependent on batteries or supplied with power through electric codes and are then used, the utilization of the devices is limited.
In order to overcome this problem, many technologies for wirelessly transmitting electric power have been developed.
Representative examples of such technologies include microwave reception technology using microwaves, magnetic induction technology using a magnetic field, and magnetic resonance technology using energy conversion between magnetic and electric fields.
Microwave reception technology is advantageous in that it can transmit electric power over a long distance because it radiates microwaves into the air through an antenna, but has limited efficiency in the transmission of electric power because radiation loss occurring in the air is great.
Furthermore, magnetic induction technology is advantageous in that it is highly efficient at transmitting electric power because it uses magnetic energy coupling based on transmitting-side primary and receiving-side secondary coils.
However, according to magnetic induction technology, in order to transmit electric power, the transmitting-side primary coil and the receiving-side secondary coil must be placed within a short distance of about several mm.
Furthermore, magnetic induction technology is disadvantageous in that the transmission efficiency of electric power changes significantly depending on the arrangement of the transmitting-side primary coil and the receiving-side secondary coil and in that the calorific value is high.
For the above reasons, there is being developed magnetic resonance technology which is similar to magnetic induction technology, but which is configured to focus energy on a specific resonant frequency using a coil-type inductor L and a capacitor C and transmit electric power in the form of magnetic energy.
The magnetic resonance technology is advantageous in that it can transmit relatively large amounts of electric power over a distance up to several meters, but requires a high quality factor.
Here, a conventional wireless energy transmission and reception loop using the magnetic resonance technology includes a disk unit configured to include two conductor plates and a dielectric, inserted between the two conductor plates, and a ring-shaped wire unit connected to both ends of the disk unit. In order to achieve a high quality factor, the intensity of electric and magnetic fields generated by the disk unit and the wire unit must be very strong.
However, in the conventional wireless energy transmission and reception loop, in order to increase the intensity of the electric and magnetic fields, the sizes of the disk unit and the wire unit should be increased, so that the application of the conventional wireless energy transmission and reception loop to an actual wireless energy transmission and reception apparatus is inappropriate.
Furthermore, since wireless energy generated by the wireless energy transmission loop is radially propagated and then transmitted, there is loss corresponding to wireless energy which is propagated to the sides and rear of the wireless energy transmission loop.
Accordingly, there is a need for an apparatus for transmitting and receiving wireless energy, which is small enough to apply to an actual apparatus for transmitting and receiving wireless energy and which can improve the transmission distance and transmission efficiency.